GB726700A - Improvements in or relating to negative impedance networks for transmission lines - Google Patents

Abstract

726,700. Negative resistance loading. MOULON, J. M. March 13, 1953 [June 6, 1952], No. 7058/53. Class 40 (4). [Also in Group XL (c)] A negative impedance device (i.e. a twoterminal network presenting an impedance having a negative real component) used for the loading of transmission line comprises a transistor amplifier having at least one impedance connected between one network terminal and the base electrode, the other network terminal being connected either directly or through a further impedance to a second electrode of the transistor. Fig. 8 shows the general circuit diagram, the terminals 6 and 7 being connected in series in the transmission line to be loaded and one at least of the impedances 3, 4, 5 having a reactive component of such a value that the reactive component of the loaded transmission line is eliminated. Practical embodiments of this circuit are shown in Figs. 11 and 12, the condensers 8 and 9 having large values and serving to block direct currents which are supplied to the transistor through the transmission line and resistors 10, 11 having large values so as not to materially affect the values of the impedances Z1, Z2, as determined by the components 3 and 5. In the arrangement of Fig. 12, the capacitative impedance 3 and the blocking condenser 9 are combined as one single 1000 pF condenser. In an alternative arrangement, Fig. 10 (not shown), negative impedances are inserted at each loading point into each conductor of a two-wire line. Fig. 13 (not shown) illustrates an arrangement employing a local power supply and coupled to the line through a transformer. Specifications 432,759 and 563,417 are referred to.